The present invention relates to a hydraulic control system for controlling the operation of a winch and more specifically relates to means for controlling the main clutch of a winch particularly suited for use with forestry vehicles, such as skidders or grapple-skidders.
A winch provided on a skidder or a grapple-skidder typically has a cable connected to a drum thereof and has a primary function of winding in or paying out the cable so as to retrieve or drop a load coupled to the cable. In the case of a grapple-skidder winch, the cable thereof is often connected to the grapple and wound in to snub the grapple against framework at the rear of the grapple-skidder so as to prevent the grapple from flopping about during transport.
The operator of the winch may, through unawareness of the situation, neglect or carelessness, continue to operate the winch to apply full driving torque to wind in a load or to snub a grapple to framework at the back of the vehicle after the load has engaged an immovable object such as a tree, a boulder or framework of the vehicle or after the grapple has become completely snubbed. Heretofore, such operation of known winches has sometimes resulted in damage to the winch drive train and/or to the grapple being snubbed.